1. Field of the Invention
This invention relates to a liquid crystal element and, more particularly, to a liquid crystal display element used in a data recording device for photographically recording some data on film and to an image formation process for the data recording by use of the element.
2. Description of the Prior Art
A data recording device for a camera has so far been known which records some data such as date on a color or monochromatic film by protecting light from a lamp or some other light source on numerals, characters or marks for indicating data displayed in a liquid crystal display element and exposing the film to the transmitted light.
Such a data recording device employs, for example, a twisted nematic (TN) type of liquid crystal element as disclosed by W. Helfrich and M. Schadt in Canadian Pat. No. 1010136. This type of liquid crystal element has a nematic liquid crystal with positive dielectric anisotropy disposed between a pair of electrode-supporting plates, the nematic liquid crystal having a helical structure in which its molecular orientation is twisted continuously by 90 degrees from one plate toward the other plate. A pair of polarizing plates in the form of a parallel nicol are attached separately to both sides of the liquid crystal element. When the operational voltage is applied, the portions of the liquid crystal in the voltage-applied regions become light-transmitting state while the other portions (the non-electrode regions and the non-voltage applied regions) are in the light-intercepting state. However, in practical operation, the portions to be shielded from light transmit a little light, which acts undesirably on a color film or monochromatic film. Thus, a vague and illegible print of data is formed on photographic paper printed by using this color or monochromatic film.
For the purpose of eliminating this defect, the following method of preventing the undesirable transmission or leakage of light has hitherto been taken: The transmission of light is reduced by placing a light-intercepting mask of thin metallic film on the outside of the electrode plates and further incorporating a dichroic dye into the liquid crystal.
However, such a light-intercepting mask of thin metallic film is prepared by a complicated and high cost process, that is, by vapor deposition of a metal to entirely cover the electrode-supporting plate and etching to remove only the areas of the metallic film on the pattern electrodes according to the photo-lithographic process. In addition, this metallic light-intercepting film needs to be insulated from the pattern electrodes, and hence a gap is inevitably formed between the metallic light-intercepting film and the electrode pattern. As a result, undesirable leakage of light from the gap takes place. Furthermore, when the electrodes of the liquid crystal element are designed to operate in the dynamic driving mode, two or more common electrodes are necessary and must be insulated one from another, thus inevitably forming a gap between them and resulting in leakage of light through the gap.